This invention relates to a flexible bag made of flexible sheet material and adapted to be self-standing after receiving flowable substances.
Many varieties of bags for flowable products such as liquids, pastes, granulates, flakes, or powders are known. Some examples are standup bags, sachets, tubing bags, paper sacks, and even box-like bags such as milk cartons. The bags can be made from coated paper, plastic sheet, metal foil, or plastic-and-foil laminate. Generally, selection of the bag material is determined by the contents of the bag. Other factors which determine the choice of materials are appearance, ability to standup when filled and/or partially filled, method in which the bags are shipped, strength requirements, need to recycle, and cost. Most known bags have not been able to sufficiently meet all these requirements.
Flexible bags are advantageous because they can be folded extremely flat in their empty state so as to require very little space. The filling of such flexible bags with the product is generally performed in an automated operation. The bag is placed upright with its dispensing opening pointing upwardly to permit a filling nozzle to be inserted thereinto. After the bag has been filled, the dispensing opening is closed by welding, sealing, or a closure.
Conventional standup bags are those with bottom xe2x80x9chorizontalxe2x80x9d panel gussets, more commonly known as bottom gussets. The gusset is heat-sealed to produce a flexible base on which the bag may stand without support. The base permits the two sidewalls or facewalls to spread at the bottom when the pouch is filled, wherein the bag is a three-panel bag that is self-standing when full or partially full of product heavy enough to bear down on the bottom pane. In most instances, the bottom panel is a separate sheet of flexible material, but some structures fold a single web sheet into a W-shape and heat-seal a base. Other standup bag structures known in the art employ sidewall folds or side gussets and overlapping flat sheet bases. These standup bags do not stand up as well because they do not have the bottom gusset and have been used more successfully for dry products than for liquids.
Such standup bags are adaptable for packaging of liquids and dry products and are suitable replacement for other types of packaging such as plastic or glass bottles, cans, and boxes. One of the advantages standup bags is that they are environmentally sound, offering source reduction of solid waste ranging from 70% to 90% by both weight and volume. As a result, the use of standup bags reduces the need for recycling landfill, and/or incineration. Another advantage of standup bags is that they offer the use of four to six color graphs for improved shelf appeal and acceptance. Standup bags further offer cost savings due to reduced transportation costs. Unlike the shipping of traditional large plastic empty containers, there is no shipping of air. There is further savings with reduced inventory save space and storage costs for containers. Standup bags take up about 1/80th the volume compared to storing an equal quantity of rigid containers.
A typical standup bag 100 generally employs two face-to-face fusion side seals and a single face-to-face across-the-top seal in addition to the bottom seals as shown in FIG. 1. When viewed from the side, the standup bag 100 looks likes a distorted triangle with the base of the triangle at the bottom 102. The across-the-top seals may be interrupted by a fitment 104, zipper closure, or other device to facilitate opening, dispensing of the contents, and reclosing. Another type of standup bag 110 includes gussets that permit the bottom to fold into a flat position, like a paper grocery sack as shown in FIG. 2.
In general, standup bags may be classified as one of two types: preformed bags and form-fill-seal bags. Preformed standup bags are made on a separate converting machine and delivered to a packager in ready-to-open, fill-and-close form, while the form-fill-seal bags are fabricated in-line by the packager from flexible roll stock materials on machines that fold the sidewalls and die-cut openings for heat sealing into the bottom section. Output speeds of intermittent motion preformed bag machines are usually faster than those on form-fill-seal machines because of multilane possibilities as well as the limiting factors of filling and sealing on the filling machines. Furthermore, it is easier to incorporate dispensing and other fitments on separate converting equipment than on inline form-fill-seal equipment. Lastly, preformed pouches tend to be more reliable in distribution performance than form-fill-seal bags such that most liquid containing standup bags to date have used preformed bags.
Representative of the prior art are the plastic bags disclosed in Kneutter U.S. Pat. No. 2,265,075, Doyen et al. U.S. Pat. No. 3,380,646, Kugler U.S. Pat. No. 3,437,258, Michel U.S. Pat. No. 3,715,074 and Bustin U.S. Pat. No. 4,353,497. Some known standup bags attempt to provide the standup capability merely by use of a simple bottom gusset alone or supplemented with seals added in the gusset structure. A simple bottom gusset sealed at its sides does not provide a normal consumer plastic bag with a sufficient standup feature. Such a plastic bag, typically made from polyethylene film less than one mil thick is too limp to stand up from the gusseted bottom.
Other objects, features, and advantages of the present invention will become more apparent to those persons having ordinary skill in the art to which the present invention pertains from the foregoing description taken in conjunction with the accompanying drawings.